Dichloroethane C2H4Cl2 is acommon industrial solvent. underground behind an abandoned plant a700m3 volume of soil is found to be contaminated withthis chemical to an average concentration of 50 ppm. a survey ofthe soil indicates that ample bacteria are present to decompose thewaste according to the following equation:
2C2H4Cl2 + 5O2---> 4CO2 + 4HCl + 2H2O
Presently, however, there is insufficient oxygen available tothe microorganisms, and therefore you decide to pump watercontaining 8 ppm O2 into the site at a rate of 50L/min.Assume that both the bacteria and dichloroethane are adsorbedirreversibly to the soil. Also assume that 10% of the suppliedoxygen is used by bacteria to degrade dichloroethane according tothe above equation, while the remaining 90% wasted to the soil orto the other microbial processes. How much time is required for theaverage concentration of C2H4Cl2 at thesite to fall to 10 ppm?
